Iain Duncan Smith was today appealing to Tory MPs not to dump him after admitting he had made mistakes during his leadership.
The embattled Tory leader has asked the party to back him in today’s vote of confidence and give him the chance to address his shortcomings.
Mr Duncan Smith was making a last ditch appeal to backbenchers to let him keep his job ahead of a secret ballot which will decide his future.
The vote was sparked by yesterday’s announcement that at least 25 MPs had written to Sir Michael Spicer, the chairman of the Tory backbench 1922 committee, calling for the move.
The result of the ballot will be announced by Sir Michael at around 7pm.
Mr Duncan Smith needs a simple majority of the votes cast to secure his position for another year.
Defeat would trigger a leadership contest which he would be prevented from standing in. The field would be open to leadership hopefuls whose names have been the subject of mounting speculation at Westminster for weeks.
Mr Duncan Smith pledged to fight on and almost the entire shadow cabinet came out in support of him last night.
Today he admitted he had made mistakes but appealed to Tory MPs to give him a second chance.
The Tory leader said he was duty bound to fight the vote of confidence and warned the party that now was not the time for “the insulting irrelevance” of a leadership contest.
Writing in today’s Times newspaper he said he had listened to what colleagues had to say about his leadership.
“I have a deeper understanding of the shortcomings of the past two years and of what needs to be done to address them. That is my second duty: To develop as a leader.
“No book has been written on how to be leader of the opposition and I have made mistakes. Not all of my staff appointments have been successful, but I have now built a team of senior advisers that can take us to the next election.”
Mr Duncan Smith’s decision to fight on plunged Westminster into 24 hours of frenzied campaigning and speculation before today’s vote.
Earlier yesterday, Mr Duncan Smith called six shadow cabinet members and officials to a strategy meeting – which his wife Betsy also attended – after being told a vote would take place.
In a statement, shadow ministers said Mr Duncan Smith had “earned the right to lead our party into the next election”.
Party chairwoman Theresa May confidently predicted that Mr Duncan Smith would win today’s vote.
But Crispin Blunt, the first Tory backbencher to break cover and call for Mr Duncan Smith to go, said the MPs had done the right thing in forcing a confidence vote.
Mr Blunt, MP for Reigate, told BBC News 24 that concerns over Mr Duncan Smith’s leadership “are real and deep – they have to be addressed”.
He said: “We have a mechanism to address them and I think the vote of confidence will settle the issue. Either Iain will then have the authority to lead us to the next general election without this wretched speculation making his position impossible, or we will select a new leader to then take us to the General Election.”
Sir Patrick Cormack, a member of the 1922 executive committee, later became the fifth MP to confirm publicly he was one of those who had written asking for today’s vote.
The others were Mr Blunt, ex-minister Francis Maude, and backbenchers Derek Conway and John Greenway.
Sir Patrick said: “I agree with the leader that this matter should be brought to a head at the earliest possible moment.
“I personally believe that his authority would be immeasurably strengthened if he won a vote of confidence.”
The stage is now set for a day of drama at Westminster, with Mr Duncan Smith having to face Tony Blair at Prime Minister’s questions in the Commons at noon, before addressing his own MPs at 2.30pm.
Senior Labour figures did not comment publicly on the Tory vote, but privately could scarcely disguise their enjoyment of another bout of Conservative in-fighting.
The Liberal Democrats said they were now the only serious opposition to the Government.